Recording device



L. GARCEAU RECORDING DEVICE Nqv. 21, 1950 Filed March so, 1946 3 Sheets-Sheet l INVENTOR. LOl/ETT GARCEAU BY y A T TOR/V5 rs Nov. 21, 1950 Filed March 30, 1946 L. GARCEAU RECORDING DEVICE 3 Sheets-Sheet 2 INVENTOR. LOVETT GA/QCEAU A T TO/QNE Y5 Patented Nov. 21, 1950 UNITED STATES PATENT OFFICE 14 Claims. 1

This invention relates to improvements in recording devices and is directed more particularly to devices for recording amplified thermionic impulses.

This application is a continuation, in part, of co-pending application Serial Number 417,865, filed November 4, 1941, for Electroencephalograph Devices, now Patent No. 2,409,033 dated October 8, 1946.

An object of the invention is the provision, of a recording device, operated by thermionic impulses and adapted to be used in multiple channel or single channel electroencephalographs, electrocardiographs, and for use in general purpose oscillographs.

A further object of the invention is the provision, of a recording device, which includes a balanced armature carried on a shaft, which is rigidly supported in spaced bearings in the device, and in which a stylus arm is pivotally secured on one end of said shaft.

A further object of the invention is the provision, in a recording device, of a movable armature and fixed pole pieces, so arranged relative to each other that the distance or air gap between the pole pieces, and the armature remains the same regardless of the deflection of the armature.

Yet another object of the invention is the provision, in a recording device, Of a single shaft rigidly supported in bearings, said shaft carryr ing an armature intermediate the ends thereof, a stylus arm secured to said shaft adjacent to the end thereof, and an arm adjacent to the opposite end thereof. connected to opposed spring means which are in turn adjustably connected to the frame of said device.

Another object of the invention is the provision, in a recording device, of an armature shaft, carrying a recording arm, a portion of one end of which is journaled at right angles to the axis of said shaft, and including a portion angular with respect to said first portion, said recording arm including spring means constantly urging said second mentioned portion in apredetermined direction.

Another object of the invention is theprovision, in a, recorder, of a magnetic circuit. one leg of which includes a pair of spaced pole pieces and another leg of which includes. a second pair of spaced pole pieces. the individual pole piecescarried on said first leg having notched portions in alignment with corresponding notched portion on, the pole pieces carried on said second leg, said magnetic circuit including an electromagnet for polarizingsaid pole pieces and in whichapivoted armature is carried on an axis parallel to said legs and positioned intermediate said legs and intermediate said pairs of pole pieces, and a fixed winding embracing said armature and adapted to be connected to an output anode of a thermionic circuit.

Another object of the invention is the provision, in a recorder, of a magnetic circuit, one leg of which includes a pair of spaced pole pieces and another leg of which includes a second pair' of spaced pole pieces, the individual pole pieces carried on said first leg being in alignment with corresponding pole pieces carried on said second leg, said pole pieces all being slotted to form on either side of the slot thereof spaced poles of like polarity, said magnetic circuit including an electromagnet for polarizing said pole pieces and consequently said poles, and in which a pivoted armature is carried on an axis parallel to said legs and positioned intermediate said legs and intermediate said pairs of pole pieces, and a pair of fixed windings embracing said armature and adapted to be connected to the push-pull output of a thermionic device.

Yet another object of the invention is the provision of a recorder which includes a field having pole pieces and an armature cooperating therewith, said field being excited electromagneticall'y' and including fixed windings influencing said armature, the connections for said windings being mounted on the device and terminating in a connection plug, said device being supported on a mounting plate, whereby said connection plug may be disconnected and the device bodily removed from any instrument with which it is as-' sociated.

In the aforesaid co-pending application, a recording device is shown as connected to the out-' put of an amplifier used in connection with an electroencephalograph. The present invention relates to improvements on a recording device such as that described in the aforesaid co-pend ing application.

Referring to the drawings:

Figure 1- is an elevation of my new and im-' proved recording device;

Figure 2'is a sectional elevation of mynewand improved recording device as seen along the lines 2--Z of- Figure 1;

Figure 3 is a view partl in section taken along the lines 33 of Figure 1;

Figure 4 is a fragmentary view of a portion of an electroencephalogra h showing my new andimproved recording device-positioned therein and showing the relation of therecording device" to the tape and the means for driving the latter;

Figure 5 is a plan view of the arrangement shown in Figure 4;

Figure 6 is a fragmentary View showing the upper end of the armature and the method of securing the recording arm thereto;

Figure 7 is a diagrammatic representation of the outlet stages of a thermionic amplifier, and by way of example showing the connections to my new and improved recorder; and

Figure 8 is a circuit diagram of my new and improved recorder showing the connections terminating in a plug adapted to be plugged into the circuit shown in Figure '7.

Referring first to Figures 1, 2 and 3, a core l0, which is highly permeable magnetically, carries an electromagnetic winding II and this core has a central hole there n to accommodate a screw I2, and a vertical leg l3 has its lo er end abutting one end of the core I8, a suitable hole having been provided therein to accommodate the screw l2. A second vertical leg l4 has its lower end abutting the op osite or left end of the core I and the screw |2 passes through the lower ends of both legs and core, and a nut I5 and a lock washer |6 are provided for securing the core and the two legs together rigidly. The vertical legs l3 and I4 are also highly permeable, magnetically. A bar I! of non-magnetic material adjacent to the winding spans the distance between the legs I3 and I4 and is secured thereto by means of screws l8. Secured on the uooer end of the leg I3 is a vertical post l9 and likewise secured to theunper end of the leg I4 is a second vertical post 20. These osts are formed of non-magnetic material and are in alignment with one another on the center lines of the legs l3 and I4. A second bar 2|, preferably formed of non-magnetic material, spans the posts I9 and 20 and is secured thereto. A hearing 22 is formed in the bar I1. and a bearing 23 is formed in the bar 2| and these bearings are in alignment with one another and form journals for a vertical shaft 24. Secured to the u per end of the leg l3 and extending slightly beyond the bar 2| are hexagonal posts 25 and 26. Likewise on the upper end of leg M are secured similar posts 27 and 28. The posts 25. 26. 21 and 28 are formed of non-magnetic material, and secured to the upper ends of these posts. by means of fiat head screws 30, is a plate member 29.

The plate 29 has a clearance hole therein in alignment with the bearings 22 and 23 and through which the upper end of the shaft 24 extends. The lower end of the shaft which journals in the bearing 22 is reduced in diameter, thereby forming a shoulder which bears against the surface of the bar I! immediately surrounding the bearing 22. On the shaft 24, beneath the bar 2|, is secured a collar 3|. The collar 3| may contact the bar 2|, and s nce the shoulder contacts the bar I! about the bearing 22, end play of the shaft is thereby eliminated. Secured to the upper end of the shaft above the plate 29, is ahead boss 32. The head boss is bored out to accommodate a bushing 32a. This bushing is formed of insulating material. Its interior bore forms a snug fit on the upper end of the shaft and its exterior forms a snug fit with the bore in the head boss 32. A set screw 33, threaded into the head boss 32, bears against the insulating bushing 32a and exerts pressure on the shaft via the insulating bushing, thereby firmly securing the head boss to the shaft 24, yet enabling the shaft and the bushing to move independently of one another in cases where undue strains are subjected to either. Several important functions of this bushing will presently be described herein.

Secured to the shaft 24 is a rectangular bar 34 which constitutes an armature. The bar 34 is preferably formed of highly permeable magnetic material yet having low retentivity and low hysteresis. Although any material having these characteristics may be used, I prefer to form my armatures from ARMCO magnetic ingot iron. This bar has a hole intermediate its ends to fit the shaft 24, and extending inwardly from one end thereof is a set screw 35 which engages the shaft 24.

Secured to the shaft 24 near the bearing 22 is a collar 36. The collar 36 is secured to the shaft 24 by means of a set screw 37. Threadedly engaging the collar 36 is a screw 38 having a flattened portion 39, which in turn has a hole 40 adjacent to the outer end thereof. A spring 4| has one end engaging the hole 40 and has its other end engaging a hole formed in a flattened portion 42 of a screw 43. The screw 43 extends through a hole formed in the leg I 3 and by means of nuts 44 and 45 the tension of the spring 4| may be adjusted and locked in any desired adjustment. One end of a second spring 46 engages the screw 38 via the hole 40, and the other end of this spring is connected to the flattened portion 47 of a screw 48. The screw 48 extends through a hole formed in the vertical leg l4, and by means of nuts 49 and 50 the tension of the spring 46 may be adjusted and secured in any adjusted relation.

Secured to the inner face of the upper end of the leg I4 is a pole piece 5|, and in alignment therewith and spaced apart therefrom is a second pole piece 52. These pole p eces and the others described below are formed of highly permeable magnetic material. The pole piece 5| has an apex 53 and formed in the apex is a slot 54 which divides the tip of the apex into two spaced hole pieces 55 and 56. The pole piece 52 is identical with the pole piece 5| and the slot in its apex is in alignment with the slot 54. Identical pole pieces, one of which is shown at 51, are secured to the vertical leg I3 near the upper and thereof, and a pole piece similar to the pole piece 52 and in alignment therewith is also secured to the upper end of the leg l3. These pole pieces are likewise provided with slots 58 like the slot 54, thereby dividing the apexes into two spaced pole pieces 59 and 68. One end of the armatures 34 is positioned in the slots 54, 58 and lies between th holes 55, 59 and the holes 55, 60. The opposite end of the armature bears the same relation to poles formed on the pole pieces 52 and the one corresponding to 57. The air gap between the upper surface of the armature and the upper pole pieces, for example 55, 59, is equal to the air gap between the lower surface of the armatures and the lower pole pieces, for example 56, 60.

The tension of the Springs 4| and 46 may be adjusted so as to postion the center line of the armature 34 coincident with a center line between the opposite poles (55, 59 for example).

Referring now to Figure 6, the head boss 32 has near the upper end thereof a cross-hole 6| formed therein. The recording arm 62 has an angular portion 53 journaled in the hole 8|. The end of the portion 63 is threaded and a nut 64 engaging the threads retains the portion 63 in the hole 6| which forms a bearing. The recording arm has a curved portion 65, a straight portion 66, and an angular portion 61 which may carry a stylus. 68. A spring 69 has a straight portion I which engages. a. radial hole II formed in the boss 32. The remainder of the spring 69 embraces the curved portion 65 of the stylus and tends to urge. the outer end downwardly, as seen in Figure. I. A bobbin I2, as may be, seen in Figure 2;, embraces the end 34 of the armature and a. second bobbin l3 embraces. the end 34 of the armature. These bobbins have spacers. M and 1.5 therebetween and may be secured toe gether by screws 16. A terminal strip 1! mounted on posts I8. and I9, mounted on the leg I4, carry terminals for the ends of the winch. ings on thebobbins I2 and I3 and for the electro-magnet. II. The terminal strip also carries a terminal from which a wire 80 extends to the head bOSs 32., said wire being connected to. the head boss by means ofa screw SI. The connec tions to the terminal strip TI will be described in conn ction with the circuit diagram.

The insulating bushing 32 in the head boss 32 serves three important functions: (1) It acts as. an insulator to insulate the boss 32 and the stylus from the frame of the device and com sequently the potential supplied to the head boss and stylus via thev Wire 80. is impressed on the stylus. (2) The insulating bushing 32 acts as a safety device to prevent undue. strains which might wreck or distort the stylus arm in case the latter becomes hung up or jammed. In such cases, any urge imparted to the shaft 24 by the armature would not effect the. stylus arm because if the urge were greater than the frictional urge of the bushing 32 on. the shaft, the. shaft could move without moving the head boss 32 and the stylus arm 66 and 3) the operator may adjust the stylus arm in either direction to bring it. to a desired zero position without having to loosen any set screws or to make any other adjustments.

The recording device, as shown in Figs. 4 and 5, is positioned in a, top panel of an electroencephalograph. The recorder. extends through a hole formed in the top plate 82 and is secured thereon by means of screws 83 extending through the plate member 29. on the recorder. The connections on the terminal strip 'I'I extend via a cable 84. to a six-pronged connector plug 85 which may be inserted in a socket (not shown) in the encephalograph. When it is desired to remove the recorder all that is necessary is to remove the screws 83, disconnect the connector plug 85., and lift the recorder out.

When the recorder is in position in the electroencephalograph its stylus 68, engages the surface of a tape 86 which is supplied from the roll of tape 81. The tape as it leaves. the roll 81 passes underneath and around a knurled roller 88 which is driven by a synchronous electric motor 89. The knurled roller 8.8 driven by the synchronous motor is geared down so that the speed of the recorderv tape past the stylus is ex.- actly three centimeters per second.

The speed of three centimeters per second for the tape was the speed given by way of example in the aforementioned copending application. However, I do not wish to be limited to that specific speed as the tape speed can be made any value within reason. For example, I have made machines to run at tape speed of one or, two inches per hour up to speeds of forty feet per second and I have developed machines with speed changes which included gear reductions enabling. the device to beset at three different speeds, and others which had continuouslyvaria ble speeds. The main thing is that whatever speed is' selected, it should preferably be a constant speed.

The tape mechanism is mounted on a plate 96 which carries a stud 0| upon which an arm is pivotally mounted. On the end of the pivotal arm 90 is a shaft 93 upon which is mounted a roller 02. The roller 92 may have a frictionless bearing between itself and said shaft. Spring means 99 urges the arm 95 in a counter-clockwise directio'rnas seen in Fig. 4, and thereby urges the roller 02 against the tape and in turn urges the tape into driven relation with the knurled roller 88.. The plate 9.6. has a depending bracket arm I00 which slides in a vertical slot [01 formed in a bracket I02 secured to the topplate 82 of the electroencephalograph. The bracket I00 has an upwardly projecting extension 9'! which has a hole 98 formed. therein and by means of which the tape mechanism may be pulled upwardly and removed. from the instrument. The plate 36 is notched out at I03 to. clear the knurled roller 88.

A cap I00 having a lateral slot [$5 formed therein embraces head boss 32 and the straight portion 56. of the recording arm extends through the slot I05. Suitable screws I06 extending through a flange I01 on the cap I04. secure it to. the, plate member 29 and this cap serves to protect the head boss and the connection 8| between it and the wire $0 from dust and-mechani cal injury.

Referring now to Fig. 8, one terminal I08 of the bobbin I2 is connected to the terminal [09 on the terminal strip I? and this in turn is connected via a wire to the prong A of the plug 85. The other terminal of the bobbin I2 is connected in common with one terminal of the bobbin I3 and these are in turn connected via a conductor III to a terminal II2 on the terminal strip 11, and this terminal is in turn connected via a Wire II3 to the prong C and the plug 85. The other terminal of the bobbin I3 is connected via a wire M4 to a terminal II5 on the strip 11 and is in turn connected via a wire [I6 to the prong B of the plug 85. The two ends of the electro-magnet winding II are connected to terminals Ill and H8 of the strip TI and these are in turn respectively connected via wires I I9 and I20 to prongs D and E of the plug 85.

The terminal I2I on the strip 11 is connected via a wire I22 to the prong F of the plug 85. The resistors I23 and I24, which may have substantially identical resistance values, have leads on corresponding ends thereof connected to the terminal I21. The leads from the other ends of these resistors are connected together by a jumper I25, and the wire 80 extending from the head boss 32; is connected to the jumper I 25.

Referring now to Fig. '7 the push-pull output stage of an amplifier isv shown together with rectifying tubes and circuits for supplying rectified D, C. potentials thereto. This, output stage. is. substantially like that shown in application Serial No. 417,865, filed Nov. 4, 1941, nowPatent No. 2,409,033, issued October 1946, above referredto.

In this circuit the output tubes are. indicated at I26 and I21. The plate of the tube I26 is con nected via a wire I29 to the terminal A of'a multiple socket I29 adapted to be engaged by the plug 85. The plate of the tube I2! is connected via a wire, I30 to the terminal B of the socket I29, and high potential rectified D. C. from the rectifier I3I is supplied via a wire I32 to the terminal C of the socket I29.

It will be obvious that when the plug 85 is inserted in the socket I29 the prong A will engage A in the socket. The prong B will engage B and the prong C will engage C in the socket. Therefore, potential will be supplied from C of the socket to the prong C on the plug and via the wire H3 this potential will be impressed via III upon the joined terminals of the bobbins I2 and I3 and current will pass via these bobbins to the terminals I09 and H on the strip TI and thence via the conductors II!) and H6, respectively to the prongs A and B and thence via the socket connections A and the wire I28 to the plate of tube I26 and via the connection B and the wire I30 to the plate of the tube I21.

Current for energizing the magnet winding II is supplied by a rectifier H33. The heaters of the tube in this rectifier are energized by the winding I34, associated with the rectifier I (which will presently be described). The plates of the rectifier tube in I33 are connected together and connected to one side of the source of current. A supply of current is brought in by means of a connector plug I36, and a suitable switch I 37 is provided for switching the amplifier off and on. The output of the rectifier I 33 is connected via wires I38 and I39 to terminals D and E, respectively, of the socket I29, so that when the plug 85 is inserted in the socket the winding II is connected to this output via the wires H9 and I20.

The rectifier I35 is connected via a wire I40 to the terminal F of the socket I29. When the plug 85 engages the socket I29, potential from the wire I40 is impressed on the wire H2 and thence to the terminal I2I on the terminal strip ll in Fig. 8. From the terminal I2I potential goes through the divided path I23, I24 to the wire 80 and thence to the head boss 32 which carries the stylus arm 66. A variable resistance I42 is connected in series with a capacitor I43 and this array is connected across the plates of the tubes I26 and I 27 and the variable resistor I42 may be varied for changing the electro-magnetic damping of the armature 34. This variable resistor acts in conjunction with the series capacitor I43 as a simple equalizing network which by means of the damping effect, reduces the tendency for the oscillograph to exaggerate its response to the natural frequency. A further effect of the network i42, I43 is to eliminate the tendency for the amplifier tubes to oscillate at a high frequency as a push-pull oscillator, by reducing the Q of the armature coils.

The leading of potential to the stylus via the wire Bil enables the device to be used With any type of electrically sensitive paper and by the use of such paper, the necessity for developing or otherwise treating the strip afterwards is eliminated. It will be understood, however, that any other type of stylus may be used as well on the device without departing from the spirit of the invention.

From the above it will be seen that my new and improved recording device is rugged yet sensitive, it has simple adjustments which may be looked after desired adjustments are obtained,

and it constitutes a unitary structure which may be bodily applied to or removed from devices with which it is to be used.

Although I have herein shown and described, by way of example, one embodiment of the invention, it is obvious that many changes in the arrangements shown and described may be made within the scope of the appended claims.

What is claimed is:

1. In a recording device, a shaft journaled therein, a bar of ferrous material carried on said shaft and having its axis substantially ninety degrees with the axis of said shaft, stylus means carried by said shaft, spaced poles of one polarity and spaced poles of the opposite polarity arrayed to influence one end of said bar, like poles arrayed to oppositely influence the other end of said bar, a stationary winding in said device embracing at least a portion of the length of said bar, and means to deliver electrical impulses to said winding for imparting deflecting forces to said bar.

2. In a recording device, a shaft journaled therein, a magnetizable bar forming an armature, said bar being mounted on said shaft with its axis disposed at an angle of ninety degrees with respect to the axis of said shaft, an arm pivotally mounted on said shaft, stylus means carried on said arm, spaced poles of one magnetic polarity and spaced poles of the opposite magnetic polarity arrayed to influence one end of said bar, like poles arrayed to influence the other end of sa'd bar, and a stationary Winding comprised of at least two bobbins one on each side of said shaft, both said bobbins embracing portions of the length of said bar, and means to deliver electrical impulses from the output of a push-pull amplifier to said stationary winding for inducing deflecting forces n said bar.

3. In a recording device, an electro-magnet having spaced parallel legs, pole pieces supported on said legs, a shaft between and having its axis parallel to said legs, an armature secured to said shaft and positioned in cooperative relation with said pole pieces, spaced supports on sad magnet including bearings for said shaft, stationary windings embracing portions of the length of said armature for magnetically influencing the same, a stylus mounted on said shaft and adapted to be moved thereby in unison with the movement of sa d armature, and balanced spring means secured to said legs and acting oppositely upon said shaft for rapidly restoring said stylus to its zero position.

4. A recording device according to claim 3 in which said balanced spring means is compr=sed of an arm extending radially from said shaft, a pair of springs secured to said arm and extending in opposite directions, and adjustable supports secured to said legs and engaging the ends of said springs.

5. In a recordng device, magnetic field means including substantially identical pole shoes each having spaced poles of like polarity, at least one of said shoes being under the influence of magnetic lines of one sign and at least another of said shoes being under the influence of magnetic lines of the oppos te sign, said shoes also being so arrayed relative to one another that the spaced poles of one of them is in alignment with the spaced poles of the other with air-gaps therebetween, a pivoted armature formed of ferrous material and having the ends thereof positioned in said air-gaps, a stationary winding embracing sa d armature and connected to receive electrical impulses from the output of a thermionic amplifier, and a stylus operatively connected to and moved by said armature.

6. In a recording device, a magnet having parallel legs, a shaft journaled in supports on said magnet and having its axis parallel to said legs,

two pairs of pole shoes mounted on said legs and influenced thereby, each of said pairs of pole shoes being positioned with an air gap therebetween, a slot formed in each of said pole shoes to form individual poles, the individual poles of each shoe of each pair being in alignment with one another, a magnetizable bar mounted on said shaft and forming an armature, one end of said bar being positioned in the aligned slots in one of said pairs and the other end being positioned in the aligned slots in the other of said pairs, and stylus means carried by said shaft and moved in unison with the movement of said armature.

7. In a recording device, an electro-magnet having spaced parallel legs, pole pieces supported on said legs, a shaft between and having its axis parallel to said legs, an armature secured to said shaft and positioned in cooperative relation with said pole pieces, spaced supports on said magnet including bearings for said shaft, stationary windings embracing portions of the length of said armature for magnetically influencing the same, a stylus mounted on sa d shaft and moved thereby in unison with the movement of said armature, balanced spring means secured to said legs and acting oppositely upon said shaft for urging said stylus toward its zero position, and a conductor connected to said stylus and leading to a source of high potential direct current.

8. In a recording device, an electro-magnet having spaced parallel legs, pole pieces supported. on said legs, a shaft between and having its axis parallel to said legs, an armature secured to said shaft and positioned in cooperative relation with said pole pieces, spaced supports on said magnet including bearings for said shaft, stationary windings embracing portions of the length of said armature for magnetically influencing the same, a stylus mounted on said shaft and moved thereby in unison with the movement of said armature, balanced spring means secured to said legs and acting oppositely upon said shaft for urging said stylus toward its zero position, and a connection between said stylus and a source of direct current, said connection including a limiting resistor.

9. In a recording device, an electro-magnet having spaced parallel legs, pole pieces supported in alignment on said legs, a shaft between and having its axis parallel to said legs, a bar armature secured to said shaft and having its ends influenced by said pole pieces, spaced supports on said magnet including bearings for said shaft, stationary windings embracing portions of the length of said armature for magnetically influencing the same, a stylus insulatedly mounted on said shaft and moved thereby in unison with the movement of said armature, balanced spring means acting oppositely for urging said armature toward its zero position, and means for supplying potential to said stylus.

10. In a recording device, an electro-magnet having spaced parallel legs, pole pieces supported in alignment on said legs, a shaft between and having its axis parallel to said legs, a bar-like armature secured to said shaft and positioned under the influence of said pole pieces, spaced supports on said magnet including bearings for said shaft, stationary windings embracing portions of the length of said armature for magnetically influencing the same, an insulating bushing mounted on said shaft, a head boss mounted on said bushing, a set screw threadedly engaging said head boss and exerting pressure on said shaft via said insulating bushing, whereby said head boss may be frictionally moved independently of said shaft for setting purposes, and a stylus sup ported on said head boss and arranged to receive potential from and to be moved thereby.

11. In a recorder, a device responsive to modulated electrical impulses, said device including a shaft, an armature on said shaft, a stationary winding embracing said armature and connected to receive said impulses, a stylus arm insulatedly supported on said shaft, and means to supply potential to said stylus without electrifying the remainder of the device.

12. In a recorder, a device responsive to modulated electrical impulses. said device including a shaft, a cross-hole in said shaft, an arm having a portion thereof journaled in said hole, spring means connected to both said arm and to said shaft for urging said arm in a predetermined direction, an insulating bushing tightly fitting said shaft, a stylus support carried on said bushing, means on said support for exerting pressure on said shaft via said bushing, and a stylus carried by said support and movable therewith, whereby potential may be supplied to said support and said stylus without electrifying the remainder of said recorder.

13. In a recording device in combination, a supporting plate, a recording movement depending from said plate and having the end of a shaft extending through said plate, a movable arm mounted on the end of said shaft and extending beyond the edge of said plate, a stylus carried by said arm, and a panel having an opening therein through which said movement may pass and having a movable tape adjacent to said opening, said device being adapted to be inserted in said opening, said plate being of a size to cover the opening and said stylus being of such length that it contacts said tape.

14. In a recorder, a device including an armature influenced by electrical impulses, a shaft in said device having an enlarged portion at one end thereof, a cross-hole formed in said enlarged portion, an arm having an angular portion thereof journaled in said hole, spring means connected to both the arm and to said shaft for urging said arm in a predetermined direction about the axis of said journaled portion, and a stylus carried by said arm and movable therewith.

LOVETT GARCEAU.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,764,363 Stalder June 17, 1930 1,870,753 Sachs Aug. 9, 1932 2,367,614 Rich Jan. 16, 1945 2,384,515 Wise Sept. 11, 1945 2,396,538 Schmied Mar. 12, 1946 2,401,160 Jewell May 28, 1946 2,412,639 Traugott Dec. 17, 1946 

